The manufacture of 0.018 micron and smaller semiconductor devices has led to the use of anti-reflective coatings. These anti-reflective coatings prevent reflection of the wavelength of interest when patterning photoresist. This allows for the formation of 0.18 micron and smaller devices and structures.
Typically, anti-reflective coatings are made of inorganic material. In one prior art fabrication process, the anti-reflective coating is deposited using plasma enhanced chemical vapor deposition, and is followed by a layer of photoresist. Subsequent patterning results in uniform and accurate exposure of photoresist. However, this process is difficult to integrate into the overall fabrication process because the anti-reflective coating is difficult to remove. More particularly, the anti-reflective coating is harder than the material commonly used to form dielectric layers, stochiometric SiO.sub.2. Also, the anti-reflective coating etches differently than stochiometric SiO.sub.2.
One method for removal of the anti-reflective coating involves the deposition of a SiO.sub.2 interlevel dielectric layer over the anti-reflective coating layer. The SiO.sub.2 is then masked, patterned and etched to form vias that expose the anti-reflective coating. The anti-reflective coating is then etched using a standard SiO.sub.2 etch chemistry. Because, SiO.sub.2 etches more easily than the anti-reflective coating, undesired removal of SiO.sub.2 may result at locations where vias are not perfected landed (i.e. misaligned) on top of metal. This undesired removal of SiO.sub.2 leads to nonuniform vias and excessively overhanging vias. This, in turn leads to nonuniform plugs and can result in less than desirable electrical characteristics.
Alternatively, a dedicated etch step can be used to remove the anti-reflective coating. This dedicated etch step is typically used following a conventional oxide etch step. One prior dedicated etch step includes a SiO.sub.2 etch step specifically tailored for etch selectivity to the inorganic anti-reflective coating. However, such prior art processes are expensive due to the additional required etch step. Also, the additional etch step may still result in undesired removal of SiO.sub.2. Moreover, the additional etch step results in disruption of the fabrication process and involves additional cost while deleteriously affecting throughput.
Thus, a need exists for a method for fabricating semiconductor devices that allows for the integration of anti-reflective coatings into the fabrication process. Also, a method for fabricating semiconductor devices is needed that will allow for the efficient and inexpensive removal of anti-reflective coatings. In addition, a method for removing a layer of anti-reflective coating is needed that does not result in undesired removal of dielectric material. Moreover, a need exists for a method for the removal of an inorganic non-reflective coating that results in minimal disruption of the fabrication process. The present invention provides a solution to the above needs.